Rotary mower including sharpener and method

ABSTRACT

A mower having cutting blades revolvable in a horizontally disposed, circular annular path about, and equally spaced from, the axis of a vertical shaft operably connected with said blades for driving them in one direction in said path. A motor on said mower is connected with said shaft for driving it at a relatively slow idling speed, and a relatively high cutting speed, and a blade supporting mechanism between said blades and said shaft automatically supports said blades in cutting positions under the influence of centrifugal force at said high cutting speed with the cutting edges of said blades directed downwardly and forwardly relative to their direction of movement. At idling speed the blades automatically rotate about horizontal axes to positions with their cutting edges directed upwardly and forwardly, and a circular sharpening stone coaxial with the vertical axis of the shaft supporting said blades is spaced above said blades for lowering to engage the bevel for the cutting edges to sharpen the blades during said idling speed, which stone is then elevated above the blades and releasably held.

United States Patent 2 [1 1 Spear ROTARY MOWER INCLUDING SHARPENER ANDMETHOD [76] Inventor: Herbert W. Spear, 1526 E. 4th St.,

Santa Ana, Calif. 92701 22 Filed: Jan. 17, 1972 21 App]. No.: 218,226

Primary ExaminerLouis G. Mancene Assistant Examiner-J. N. EskovitzAttorney-Mark Mohler, Dirks B. Foster, Bruce W. Schwab et al.

[111 2 3,738,092 June 12, 1973 [57] ABSTRACT A mower having cuttingblades revolvable in a horizontally disposed, circular annular pathabout, and equally spaced from, the axis of a vertical shaft operablyconnected with said blades for driving them in one direction in saidpath. A motor on said mower is connected with said shaft for driving itat a relatively slow idling speed, and a relatively high cutting speed,and a blade supporting mechanism between said blades and said shaftautomatically supports said blades in cutting positions under theinfluence of centrifugal force at said high cutting speed with thecutting edges of said blades directed downwardly and forwardly relativeto their direction of movement. At idling speed the bladesautomaticallyrotate about horizontal axes to positions with theircutting edges directed upwardly and forwardly, and a circular sharpeningstone coaxial with the vertical axis of the shaft supporting said bladesis spaced above said blades for lowering to engage the bevel for thecutting edges to sharpen the blades during said idling speed, whichstone is then elevated above the blades and releasably held.

3 Claims, 7 Drawing Figures SUMMARY sitions for sharpening while theblades are revolving about the axis of the power driven shaft supportingthem, and are moved to a sharpening position for engagement with asharpening stone or sharpening device that is supported on the mower formovement into sharpening engagement with the blades. The foregoing isaccomplished by the operator at the handle of the mower while the moweris on the ground in mowing position and the blades are revolved underpower from the motor of the mower.

Another object of the invention is the provision of structure in arotary type mower in which an annular sharpening stone or device,coaxial with the vertical axis of revolution of the blades, is supportedabove the circular path of the blades, and which blades are sup portedfor movement, during their aforesaid revolution, from cutting positionswith their cutting edges facing forwardly and downwardly relative to thedirection of said revolution, to sharpening positions with said cuttingedges facing forwardly and upwardly for engagement of the bevel alongsaid cutting edges with said stone when the latter is lowered only whensaid blades are driven by the mower motor at relatively slow idlingspeed compared to their movement at cutting speed. Thus substantiallyeliminating the danger of detempering the blades.

A still further object of the invention is the provision of structure ina rotary type mower for safely and quickly sharpening the blades whilethey are revolved under power from the motor while the operator is atthe handle of the mower and the latter is on the ground in mowingposition.

An added object is the provision of an improved method for sharpeningthe blades on a rotary type mower by utilizing the centrifugal forcedeveloped at the blades at cutting speed for maintaining the blades incutting positions, and for automaticallymoving the blades from cuttingto sharpening positions under a constantly applied force overcoming saidcentrifugal force at a predetermined rate of revolution of said bladesbelow said cutting speed.

Other objects and advantages will appear in the description anddrawings.

I DESCRIPTION OF DRAWINGS ening positions against the sharpening stone.

FIG. 4 is a fragmentary enlarged detached end view of one of the cuttingblades in sharpening position.

FIG. 5 is a view similar to that of FIG. 4 with the blade in cuttingposition.

FIG. 6 is an enlarged cross sectional view along line 6-6 of FIG. 3.

FIG. 7 is an enlarged, fragmentary, side elevational view of themanually graspable control element adjacent the outer end of the mowerhandle for raising and lowering the sharpening stone.

DESCRIPTION OF THE DISCLOSURE Referring to FIG. 11 the mower housing isgenerally designated 1, being generally circular and having side wallsand a top wall and an open lower side. Ground wheels 2 support thehousing l for movement spaced over the ground, and the housing includesa conventional motor or internal combustion engine 3 having a drivenshaft 4 that extends vertically downwardly into housing 1. The motor issubstantially centrally posi-; tioned on the housing and is of the typeadapted to be controlled by an operator for driving shaft 4 at arelatively slow idling speed, or at a relatively high cutting speed. Theforegoing structure is common in rotary mowers, and is well known in thetrade.

The term rotary mower, as used herein, refers to the type that employscutting blades operably connected with a motor for revolving about avertical axis in a substantially horizontal circular path spaced abovethe ground. Whether or not the ground wheels are motor drivenis.immaterial, inasmuch as the invention is applicable to either type.

A horizontally elongated blade supporting member 5 (FIG. 3) is centrallysecured between its ends to the lower end of a vertical tube 6 that, inturn, is releasably secured by a bolt 7 to the shaft 4. Thus the member5 projects radially outwardly relative to the axis of shaft 4.

The radially outwardly projecting ends of member 5 are tubular, therebyproviding bores 8 open at their outer ends (FIG. 3). A cap 9 isthreadedly secured on each of the outer ends of the blade supportingmember 5, each cap being formed with a central opening providing abearing through a shaft 10 rotatably and reciprocablyextends, and fromwhich cap the outer end portion of said shaft projects.

Each shaft 10 is flat on one-side adjacent its outer terminal end and acutting blade 1 1 is removably secured against the flattened side ofsaid shaft by any suitable means, such as flat head Allen screws (FIG.5).

Each blade 11 is a flat sided metal strip extending transversely acrossthe flat side of each shaft adjacent to one end portion 12 of the strip,the end portion 12 being much shorter than the remainder 13 of thestrip. The longer portion of each strip has its terminal outer end edgebevelled on its upper side to form a cutting edge 14. Said portion 13extends angularly from portion 12 to the side of the blade against whichthe shaft 10 is secured.

The cutting edges 14 of blades 11 at opposite ends of the member 5 facein opposite directions to the leading relative to the direction ofmovement of the blades upon revolving when shaft 10 is rotated. Saidlonger portions of the blades that have the cutting edges at theirterminal ends extend slantingly downwardly, and forwardly relative todirection of movement of the blades about the axis of shaft 4, which isthe cutting position of each blade. In this cutting position, theportion 12, or tail of each blade extends upwardly (FIG. 5).

Each shaft 10 has a cylindrical head 18 (FIGS. 3, 6) on its inner end,which head is rotatably and reciprocably fitted within bore 8 of member5. The walls of said member are formed with a helically extending slot19 in opposite sides along the portions of bore 7 within which the heads18 are movable, and a pin 20 (FIG. 6) extends transversely through eachhead 18 and projects at its ends into the slots. A skirt or unthreadedextension 22 of each cap 9 extends across said slots and the ends ofpins 20 (FIG. 3).

The directions and lengths of slots 19 are such that when the projectingends of the pins are at one of the outer ends of the slots the bladeswill be in the cutting position of FIG. 5, and when the pins are at theopposite ends of the slots, the blades will be in the full linepositions of FIGS. 3 and 4. Axial movement of the shafts 10 in anoutward direction will effect rotation of the blades to the cuttingposition shown in FIG. 5.

An expansion spring 23 reacts between the head of each cap 9 and thehead 18 on each shaft 9 to yieldably urge each of the blades 14 out ofcutting position to the position shown in FIG. 4.

A horizontally disposed circular metal disc 24 (FIG. 3) is positionedwithin the housing 1 coaxial with shaft 4 and spaced above the member 5.This disc has an annular sharpening stone 25 bonded or secured to itslower surface, and which stone is coaxial with the disc 24. The circularinner and outer peripheries of the stone 25, at the least, define theinner and outer boundaries of the annular path of the cutting edges ofblades 11. It is accordingly seen that if the stone is lowered from theupper broken line position 26 (FIG. to the full line position, theupwardly directed bevel 27 (FIG. 4) along the cutting edge 14 of eachblade will engage the stone, and said blade will be sharpened duringrevolution of the blade about the axis of shaft 4.

Vertical rods 28 are secured at their lower ends to the metal disc 24and slidably extend upwardly through openings in the upper wall ofhousing 1 (FIG. 3). Preferably these rods are at equally spaced pointsaround the disc 24 so that the disc and stone 25 will remain in auniform plane parallel with the path of blades 10 during raising andlowering said disc.

Upstanding supports 29 are rigid relative to housing 1, there being onesupport adjacent to and spaced rearwardly of each upwardly projectingrod 28. The words rearwardly" and forwardly" and words of similarconnotation are used with respect to the normal direction of movement ofthe mower during cutting (FIGS. 1, 2).

A crank 30 has one arm 31 pivotally connected to each support 29 andprojects forwardly of said support with the other arm 32 pivotallyconnected to the upper end of each rod 28.

The body of the mower, which includes the housing 1, has a U-shapedhandle generally designated 35, providing a pair of arms 36. Theterminal forward end portions of said arms are connected at 32 withsuitable brackets connected with said body. Said handle extendsrearwardly from its forward end, and the closed end 37 of the U at therear end of the handle provides a bar for manual grasping by anoperator.

The conventional motor or engine controls (not shown) extend along thehandle to a point within reach of the operator, so the speed of theengine or motor may be manually regulated for idling when the mower isstationary and for operating at a relatively high speed when the moweris moved for cutting. The rate of revolution of the blades is relativelyslow when the motor is idling and the mower is stationary, and isrelatively fast when the mower is moved for cutting. This condition isthe same whether the mower is manually moved or is motorized.

A control rod 38 extends along one of the handles 36 to a point adjacentits rear end where it is pivotally connected at 39 with a manuallygraspable control handle 40, the latter being pivoted at 41 to asuitable segment 42 rigid with the arm 36 adjacent thereto. (FIG.7)

Said rod 38 is connected at its forward end with a horizontal cross rod43 (FIG. 1).

I claim:

1. In a rotary mower that includes a wheel mounted, downwardly openinghousing and a vertical shaft rotatably depending in said housing havingradially outwardly extending arms each supporting a cutting blade at itsouter end for movement of the blades in an annular path in one directionat a relatively low idling speed and at a relatively high cutting speed,each blade having a cutting edge facing in said one direction, and amotor on said housing manually controllable for operation at arelatively low idling speed and a relatively high cutting speed, saidmotor being connected with said shaft for rotating said shaft, and armsas a unit about the axis of said shaft for moving said blades in saidpath at an idling speed and at said cutting speed, the improvementcomprising:

a. blade supporting means movable under the influence of centrifugalforce upon movement of said blades in said annular path at said cuttingspeed for moving said blades about the axes of said arms from elevatednon-cutting positions of the cutting edges of said blades to loweredcutting positions of said cutting edges and vice versa,

b. yieldable means reacting between said blade supporting means and saidarms for moving said blades from said lowered positions of their cuttingedges to elevated non-cutting positions of said cutting edges upon thesaid blades moving in said annular path at said idling speed,

c. an annular, planar blade sharpening stone coaxial with said shaft andpath extending over and parallel with the plane of the latter,

d. means supporting said sharpening stone for downward movement to asharpening position with engagement with said blades along their cuttingedges when said edges are in said elevated non-cutting positions forsharpening said blades while they are moving in said path at said idlingspeed, and

e. means connected with said stone for moving the latter downwardly toits said sharpening position and vice versa.

2. In a rotary lawn mower as defined in claim 1;

f. said arms having a longitudinal bore in the outer end portion of eacharm, and the blade supporting means for each blade comprising a shaftrevolvable and reciprocably supported in each bore,

g. guide means respectively on said end portion of each arm and on saidshaft in engagement with each other for affecting movement of said shaftand blade along a helical path upon movement of said shaft outwardlyunder said influence of centrifugal force for rotating each of saidblades to move its cutting edge to said lowered cutting position,

secured thereto and positioned thereover,

b. said means supporting said sharpening stone for vertical reciprocablemovement including vertical rods secured at their lower ends to saidplate and extending through said openings in said upper wall of saidhousing,

'. and manually actuatable means connected with said rods and accessibleto an operator in operative position for operating said mower and forregulating the speed of said motor for raising and lowering said rodsand consequently said stone.

1. In a rotary mower that includes a wheel mounted, downwardly openinghousing and a vertical shaft rotatably depending in said housing havingradially outwardly extending arms each supporting a cutting blade at itsouter end for movement of the blades in an annular path in one directionat a relatively low idling speed and at a relatively high cutting speed,each blade having a cutting edge facing in said one direction, and amotor on said housing manually controllable for operation at arelatively low idling speed and a relatively high cutting speed, saidmotor being connected with said shaft for rotating said shaft, and armsas a unit about the axis of said shaft for moving said blades in saidpath at an idling speed and at said cutting speed, the improvementcomprising: a. blade supporting means movable under the influence ofcentrifugal force upon movement of said blades in said annular path atsaid cutting speed for moving said blades about the axes of said armsfrom elevated non-cutting positions of the cutting edges of said bladesto lowered cutting positions of said cutting edges and vice versa, b.yieldable means reacting between said blade supporting means and saidarms for moving said blades from said lowered positions of their cuttingedges to elevated non-cutting positions of said cutting edges upon thesaid blades moving in said annular path at said idling speed, c. anannular, planar blade sharpening stone coaxial with said shaft and pathextending over and parallel with the plane of the latter, d. meanssupporting said sharpening stone for downward movement to a sharpeningposition with engagement with said blades along their cutting edges whensaid edges are in said elevated noncutting positions for sharpening saidblades while they are moving in said path at said idling speed, and e.means connected with said stone for moving the latter downwardly to itssaid sharpening position and vice versa.
 2. In a rotary lawn mower asdefined in claim 1; f. said arms having a longitudinal bore in the outerend portion of each arm, and the blade supporting means for each bladecomprising a shaft revolvable and reciprocably supported in each bore,g. guide means respectively on said end portion of each arm and on saidshaft in engagement with each other for affecting movement of said shaftand blade along a helical path upon movement of said shaft outwardlyunder said influence of centrifugal force for rotating each of saidblades to move its cutting edge to said lowered cutting position, h.said shaft having an enlargement thereon within said bore and each armhaving an apertured cap at its outer end through which said shaftrotatably and reciprocably extends, and i. said yieldable means being anexpansion spring around said shaft between said enlargement and saidcap.
 3. In a lawn mower as defined in claim 1; f. said housing having agenerally horizontally disposed upper wall supporting said motor, and aplurality of openings formed in said upper wall around said motor, g.said stone including a rigid backing plate of metal secured thereto andpositioned thereover, h. said means supporting said sharpening stone forvertical reciprocable movement including vertical rods secured at theirlower ends to said plate and extending through said openings in saidupper wall of said housing, i. and manually actuatable means connectedwith said rods and accessible to an operator in operative position foroperating said mower and for regulating the speed of said motor forraising and lowering said rods and consequently said stone.